Analysis on the structure and electrical property of PI/MWNTs films

In this paper, Polyimide/mutil-walled carbon nanotube(PI/MWNTs) nanocomposites were fabricated by an in-situ polymerization process. Scanning electron microscopy(SEM) was used to analyze the microstructure of the surface and cross-section shape. The relationship between the structure of the films and the electrical property including the dielectric constant ɛr, the dielectric loss factor tanδ and the volume resistivity was researched. The results showed that the addition of acid-modified MWNTs into a polyimide matrix led to some variations in the dielectric properties, dielectric constant increased at first then decreased with the increase of the content of MWNTs, the variation of dielectric loss is not obvious when doping content of MWNTs is lower than 1.5wt%, with the content of MWNTs increased continuously, the dielectric loss improved significantly. As the doping content reached 11.598wt%, the volume resistivity of PI/MWNTs films sharply decreased to 1.96×10⁸Ωm.